THE ARMY- WORM. 17 



served. The one shown in fig. 9 inserts a number of eggs 

 in the army-worm and the resulting cocoons, which are of 

 a white color and surrounded with loose silk, could be found 

 everywhere in the fields fastened to all kinds of plants, to 

 sticks and even to loose pieces of sod. The illustration 

 shows some of these cocoons fastened to a leaf, a single co- 

 coon greatly enlarged, and also the adult parasite, {Ajxn/- 

 teles C07ig7'egatus Say) , \Yh\ch leaves the cocoon by a neath^ 



Fig. 9. — Apanteles congregatus Say: its cocoons, natural size, and a single 

 cocoon with loose cap. Enlarged. Original. 



made circular opening covered by a tight-fitting lid. When 

 we dig in the ground after the larger part of the army- 

 worms have disappeared, we find, besides the red pupa of the 

 army-worm and a large number of dying ones, also numer- 

 ous very tough, brown, oblong-oval, silken cocoons from 

 which the parasite ( Opliion 'purgatum Say) shown in fig. 10 

 issues in due time. When we visit a field invaded by army- 

 worms w^e soon see that the worms have by no means everj^- 



